The most sophisticated mechanical device of ancient Greece may finally be giving up its secrets. Researchers have long known the so-called Antikythera mechanism was a calendar of sorts that represented the positions of the sun and moon using a series of gears. In its complexity it outshined all other objects for a thousand years following its creation sometime around the second century B.C. Now an international consortium of researchers has probed the machine’s corroded fragments with sophisticated x-ray and light imaging tools to uncover the true sophistication of this geared wonder.
The device could predict eclipses as well as reproduce a subtle irregularity in the moon’s orbit, they reveal. Moreover, it may have been able to represent the motions of the planets, although the necessary gears seem to be long gone. They also confirm a prior hypothesis that the device relied on spiral grooves to count off certain lunar cycles. “We don’t know what it was for but we do believe we know what it did,” says astronomer Mike Edmunds of Cardiff University in Wales.
Divers recovered the Antikythera instrument in 1901 from a 2,000-year-old shipwreck that had sunk beneath the Mediterranean Sea, midway between Greece’s Peloponnesian peninsula and the island Crete. What they found was a hunk of calcified bronze gears and other fragments, along with a decayed wooden box that had housed the mechanism. In pioneering work begun in the 1950s (and first described in a 1959 Scientific American article), the late science historian Derek Price reasoned that this encrusted mess was a solar-lunar calendar. The box would open in the front to reveal a dial with rotating gear-driven pointers to mark off the sun’s position and the phases of the moon. The back of the device contained two dials that counted off other cycles.